How Fermented Foods & Probiotics in Gut Health

Fermentation has been used as a preservation method for thousands of years, but the benefits go beyond keeping your food safe to eat. Pickled vegetables and probiotic yogurt are just a few fermented foods that have recently become popular for their gut health benefits. But what exactly is the role of fermented foods in gut health, and why should you eat them? In this two-part fermented food blog series, I’m going to help you understand why fermentation is more than just a buzzword. My amazing student, Amy Pun helped to pen this article – she’s pretty fantastic so be sure to thank her for her brains in the comments!

It is important to understand the difference between prebiotics, probiotics, and fermented foods.

Probiotics are a type of “good” bacteria that keep your gut healthy. They can be found in some fermented foods containing active live cultures , like yogurt. It may surprise you, but not all fermented foods can make probiotic claims!

The World Health Organization (WHO) classifies probiotics as “live organisms which when administered in adequate amounts confer a health benefit on the host” 1. This means that probiotic foods are required to have an adequate number of good bacteria with scientifically proven benefits on health 11.

What does this mean? Probiotic foods must have the right TYPE (proven to have health benefit) and AMOUNT of bacteria (# of bacteria needed to infer a health benefit, alive until the end of shelf life) to be classified as probiotics when advertising.

Although some fermented foods such as kombucha and sauerkraut may contain living organisms, these foods may not have the right bacterial strains or enough beneficial bacteria to be proven to be beneficial for the gut.

It’s important to understand that having a fermented food does not mean it can be classified as ‘probiotics’. In Canada the use of the word probiotics means that the food HAS to have met the standards of which to be called probiotic. HOWEVER! watch (especially on social media!) for the inappropriate use of the word ‘probiotics’ – it happens more often than you think!

Prebiotics are a substrate that is selectively utilized by host microorganisms conferring a health benefit 2.

Prebiotics, like onions, bananas, and oats have dietary fibre or nutrients that feed the bacteria in your gut and release metabolic by-products (like short chain fatty acids) that maintain health and prevent disease.

Not all fermented foods are prebiotics – however, many fermented foods are made with prebiotic containing ingredients (like sauerkraut), or whose process of fermentation creates prebiotics (fermented dairy).

Fermented foods are foods that have undergone chemical reactions by bacteria and yeast to produce metabolic by-products such as alcohol, carbon dioxide, and acetic acid, giving them characteristic flavours and improved storage-life.

Now you might be asking: why should I eat fermented foods when prebiotic and probiotic supplements are available on the market? Shouldn’t I just take a probiotic?

Answer: Most of the time, (and at this stage in research), probiotic pills aren’t necessary for everyone and anyone. However, you may benefit from a probiotic pill if you’re looking to manage a very particular symptom or condition. For example, I regularly may use probiotics in my IBD or IBS patients to see if we can’t get increased symptom control.

Probiotic pills are often used for managing symptoms of a very specific condition – for example, diarrhea post antibiotic use. They contain a determined amount and type of bacteria that has been proven for the claims they are making.

They can be helpful in symptom management but are likely not necessary to take day in and day out. I always say when you take a pill, you should ‘measure’ your outcomes. What is the purpose of taking it, and are you better, worse or the same when you stop taking it? A doctor, dietitian, or pharmacist can help you sort this out.

I always say choose whole foods. This goes for your probiotics (like yogurt & fermented dairy), prebiotics (my faves are listed below!), and fermented foods. Variety is KING when it comes to gut health! I like to encourage my clients to ‘eat something living every day!’. Of course this isn’t always practical, but I encourage my patients to keep it top of mind.

Our favorite prebiotic foods include:

Garlic

Onion

Artichokes

Asparagus

Pulses (chickpeas, beans, lentils etc.)

Bananas

Dried fruit

Whole grains

Fermented dairy

Kimchi, sauerkraut

*note, many of these are FODMAP containing and are not appropriate during elimination and reintroduction. Talk with your dietitian for more information.

Recently, the definition of prebiotics has been expanded to include certain types of fats from both plants and animals, polyphenols, and antioxidants – all the more proof we need a variety of foods in our diet!

Why Should You Eat Fermented Foods

We encourage people to include fermented foods in their diet not only to add to that variety, but also because of the metabolic by-products of fermentation, and because if the product has living bacteria – those helpful bugs can help in metabolizing prebiotics you consume – potentially having benefits for your gut health! I am personally SO excited to see where the research goes in regards to fermented foods.

This ties RIGHT into what I always say about gut health and diet – we may not know all the answers yet, but time and time again, a varied, whole foods diet is showing beneficial effects on gut health.

Three Benefits of Fermented Foods & Probiotics

Beneficial metabolic end-products in fermented foods

The bacteria in fermented foods produce metabolic end-products to enhance gut health. A lot of people think, “If I eat fermented foods, the bacteria will camp out in my gut and make me healthier.” Not quite.

When food undergoes fermentation by bacteria, instead of the bacteria staying in the gut forever, it can create beneficial metabolic by-products conducive gut health. Lactic acid is one of these end-products found in dairy foods 3,4.

Recent studies have found that lactic acid can reduce inflammation and provide antioxidants to intestinal cells 3,4. Different strains of bacteria may produce other beneficial end-products 3. For instance, several B vitamins such as folate (B9), riboflavin (B2) and B12 are made by bifidobacteria (a type of good bacteria) found in fermented plant and dairy foods 3,4. Furthermore, amino acids and derivatives from fermented dairy products have been shown to stimulate the brain and immune system in a positive way3.

Prevention and treatment of disease with fermented, probiotic foods

Probiotic foods such as probiotic yogurts can prevent and help manage gut infections and diarrheal disease. Lactobacillus spp. in the yogurt produce lactic acid, which increases the acidity of the intestine to inhibit the growth of bad bacteria and pathogens such as Salmonella or Escherichia coli (E. coli) in your body 5.

Maintaining a healthy gut microbiome through consumption of these foods may reduce the risk of various intestinal pathogens by preventing and helping to treat microbial infections 4.

As well, bacterial enzymatic hydrolysis in fermented food has been shown to increase the production of short-chain fatty acids (SCFA) to maintain the proper pH in the colonic lumen. Appropriate pH prevents pathological changes in the mucous cells of the large intestine and reduces your risk of developing colon cancer 5.

Symptomatic relief for IBS (& other health conditions!)

Probiotics can improve tummy symptoms for individuals with irritable bowel syndrome (IBS). Even though the actual cause of IBS remains unknown, several studies found that microflora imbalance in the gut may result in IBS 6,7.

These studies revealed that individuals with IBS have a higher number of bad bacteria and a lower number of good bacteria in their gut 6. Clinical trials suggest that functional foods like yogurt with bifidobacteria (a type of good bacteria) may improve gut symptoms such as discomfort, distension, bloating, and constipation 8, 9.10.

Many fermented foods and probiotics have been researched for use in managing other conditions as well 8. For instance, regular yogurt consumption has been shown to reduce the risk of type 2 diabetes, cardiovascular disease and overall mortality 3.

Take Away Message

Regular consumption of fermented and probiotic foods has the potential to optimize gut health – however, probiotic bacteria will not ‘set up shop’ in your gut forever, and do get excreted from your body over time.

If you stop eating fermented foods the benefits will ‘wear off’ over time, which is why we encourage our clients to consume a range of probiotic and fermented foods.

We like to say ‘eat something living every day’. Of course, this recommendation needs to be practical so start with an amount of fermented and probiotic containing foods that works for you!

What else can we do to have lasting benefits to promote gut health? In the next part of our two-part series on fermented foods, we will discuss how to optimize gut health by nurturing your own set of good bacteria with prebiotic foods.